Treatment of cancer by inhibition of IGFBPs and clusterin

ABSTRACT

Agents that reduce the amount of IGFBP-2 and/or IGFBP-5 and that are known to be useful in the treatment of cancer result in increased expression of the protein clusterin. Since clusterin can provide protection against apoptosis, this secondary effect detracts from the efficacy of the therapeutic agent. In overcoming this, the present invention provides a combination of therapeutic agents that is useful in the treatment of cancer. The combination includes an agent that reduces the amount of IGFBP-2 and/or IGFBP-5 and that stimulates expression of clusterin as a secondary effect, and an oligonucleotide that is effective to reduce the amount of clusterin in cancer cells. In some embodiments of the invention, the agent that reduces IGFBP-2 and/or IGFBP-5 is a bispecific antisense species. The oligonucleotide may be an antisense oligonucleotide or an RNAi oligonucleotide.

This application is continuation-in-part of U.S. patent application Ser. No. 10/346,493, filed Jan. 17, 2003, which claims the benefit of U.S. Provisional Application No. 60/350,046 filed Jan. 17, 2002. This application also claims the benefit of U.S. Provisional Applications 60/522,948 filed Nov. 23, 2004 and 60/522,960 filed Nov. 24, 2004. All of these applications are incorporated herein by reference.

FIELD OF THE INVENTION

The present application relates to a method for treating cancer in a mammalian subject using a combination of therapeutic agents, one of which is an oligonucleotide effective to reduce the amount of clusterin, also known as testosterone-repressed prostate message-2 (TRPM-2) in the cancer cells, and the other of which reduces expression of insulin-like growth factor binding protein 2 (IGFBP-2) and/or insulin-like growth factor binding protein 5 (IGFBP-5), and also stimulates the expression of clusterin as a consequence of its action on the target. By way of non-limiting example, the agent that reduces IGFBP-2 and/or IGFBP-5 may be a bispecific antisense that inhibits IGFBP-2 and IGFBP-5 expression.

BACKGROUND OF THE INVENTION

After lung cancer, breast cancer is the second leading cause of cancer deaths in women. According to the World Health Organization, more than 1.2 million people will be diagnosed with breast cancer this year worldwide, and The American Cancer Society estimates that in 2004, over 200,000 women in the United States will be diagnosed with invasive breast cancer (Stages I-IV), and about 40,000 women and almost 500 men will die from breast cancer in the United States in 2004.

Prostate cancer is the most common cancer that affects men, and the second leading cause of cancer deaths in men in the Western world. Because prostate cancer is an androgen-sensitive tumor, androgen withdrawal, for example via castration, is utilized in some therapeutic regimens for patients with advanced prostate cancer. Androgen withdrawal leads to extensive apoptosis in the prostate tumor, and hence to a regression of the disease. However, castration-induced apoptosis is not complete, and a progression of surviving tumor cells to androgen-independence ultimately occurs. This progression is the main obstacle to improving survival and quality of life, and efforts have therefore been made to target androgen-independent cells. These efforts have focused on non-hormonal therapies targeted against androgen-independent tumor cells, however as of a 1998 report, no non-hormonal agent had improved survival. Oh et al., J. Urol 160: 1220-1229 (1998) Alternative approaches are therefore indicated.

Ovarian cancer is the seventh most common cancer and the fourth leading cause of death after lung and bronchus, breast, and colorectal cancers among U.S. women. A woman's risk of getting ovarian cancer during her lifetime is about 1 in 58. The risk of getting this cancer and dying from it is 1 in 98.

Colorectal cancer, a diagnosis which comprises both cancer of the colon and the associated rectal region, is the second leading cause of cancer death in the U.S.

Standard treatments for these various cancers include surgery, radiation, chemotherapy and hormonal therapies. Each of these treatments has drawbacks including surgical risks, illness and loss of productivity associated with radiation or chemotherapy, reproductive and hormonal side effects, and unreliable survival rates.

Thus cancer is a serious disease, fatal in many cases, and requires improved treatments to reduce fatalities and prevalence.

Clusterin or “TRPM-2” is a ubiquitous protein, with a diverse range of proposed activities. In prostate epithelial cells, expression of clusterin increases immediately following castration, reaching peak levels in rat prostate cells at 3 to 4 days post castration, coincident with the onset of massive cell death. These results have led some researchers to the conclusion that clusterin is a marker for cell death, and a promoter of apoptosis. On the other hand, Sertoli cells and some epithelial cells express high levels of clusterin without increased levels of cell death. Sensibar et al., (1995)[1] reported on in vitro experiments performed to more clearly elucidate the role of clusterin in prostatic cell death. The authors used LNCaP cells transfected with a gene encoding clusterin, and observed whether expression of this protein altered the effects of tumor necrosis factor α (TNFα), to which LNCaP cells are very sensitive. Treatment of the transfected LNCaP cells with TNFα resulted in a transient increase in clusterin levels for a few hours, but these levels had dropped by the time DNA fragmentation preceding cell death was observed.

United States published patent application US 20030166591 discloses the use of antisense therapy which reduces the expression of clusterin for the treatment of cancer of prostate and renal cell cancer. Seq. ID Nos. 4, 5, and 12 herein are shown in this reference to be operative for the stated purpose of reducing the expression of clusterin, and are identified in the reference as Seq. ID Nos. 4, 5, and 12, respectively.

U.S. Pat. No. 6,383,808 discloses compositions, particularly oligonucleotides, and methods for modulating the expression of clusterin. Seq. ID Nos. 54-123 herein are shown in this reference to be operative for the stated purpose of modulating the expression of clusterin, and are identified in U.S. Pat. No. 6,383,808 as Seq. ID Nos. 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 69, 70, 71, 72, 73, 74, 76, 78, 79, 80, 82, 83, 84, 85, 86, 87, 88 and 89, respectively.

United States published patent application 2004096882 discloses RNAi therapeutic probes targeting cancer associated proteins including clusterin. Seq. ID Nos. 36, 37, and 22-43 herein are shown in this reference to be operative to reduce clusterin, and are identified in United States published patent application 2004096882 as Seq. ID Nos. 1-16, 58, 59, 61, 62, 64, 65, 67, and 68, respectively.

United States published patent application US2004053874 discloses antisense modulation of clusterin expression. Seq. ID Nos. 54-123 herein are shown in this reference to be operative for the purpose of modulating the expression of clusterin, and are identified in United States published patent application US2004053874 as Seq. ID Nos. 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 69, 70, 71, 72, 73, 74, 76, 78, 79, 80, 82, 83, 84, 85, 86, 87, 88 and 89, respectively.

United States published patent application US 2003166591 discloses clusterin antisense therapy using an oligonucleotide having 2′-O-(2-methoxy)ethyl modifications. Seq. ID Nos. 4, 5, and 12 herein are shown in United States published patent application US 2003166591 to be operative for reducing the expression of clusterin, and are identified in United States published patent application US 2003166591 as Seq. ID Nos. 4, 5, and 12, respectively.

United States published patent application US 2003158130 discloses the use of chemotherapy-sensitization and radiation-sensitization of cancer by antisense clusterin oligodeoxynucleotides. Seq. ID Nos. 4, 5, and 12 herein are shown in United States published patent application US 2003158130 to be operative for reducing the expression of clusterin, and are identified in United States published patent application US 2003158130 as Seq. ID Nos. 4, 5, and 12, respectively.

SUMMARY OF THE INVENTION

Applicants have found that agents that reduce the amount of IGFBP-2 and/or IGFBP-5 and that are known to be useful in the treatment of cancer result in increased expression of the protein clusterin. Since clusterin can provide protection against apoptosis, this secondary effect detracts from the efficacy of the therapeutic agent. In overcoming this, the present invention provides a combination of therapeutic agents that is useful in the treatment of cancer. The combination comprises an agent that reduces the amount of IGFBP-2 and/or IGFBP-5 and that stimulates expression of clusterin as a secondary effect, and an oligonucleotide that is effective to reduce the amount of clusterin in cancer cells. In some embodiments of the invention, the agent that reduces IGFBP-2 and/or IGFBP-5 is a bispecific antisense species. The oligonucleotide may be an antisense oligonucleotide or an RNAi oligonucleotide.

The combination of the invention is useful in a method for treating cancer in a mammalian subject, comprising administering to the subject the agent that reduces IGFBP-2 and/or IGFBP-5 and an oligonucleotide effective to reduce the amount of clusterin in the cancer cells.

The cancer may be breast cancer, osteosarcoma, lung cancer, pancreatic cancer, salivary gland cancer, colon cancer, prostate cancer, endometrial cancer, and bladder, for example.

Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate embodiments of the invention,

FIG. 1 the amount of IGBFP-2 and IGBFP-5 expression observed in LNCaP and PC3 cells, respectively, upon administration of one of three bispecific antisense oligonucleotides, a mismatch control (MM), or no olignucleotide (control).

FIGS. 2A-E shows inhibition of IGFBP-2 and 5 in prostate cancer and bone cells using various antisense oligonucleotides.

FIGS. 3 and 4 show real time PCR results for levels of IGFBP-2 and IGFBP-5 in RT4 bladder cancer cells after treatment with antisense oligonucleotides of the invention.

FIG. 5 shows results of real time PCR measurement of IGFBP-5 in MSF human fetal fibroblast cells after antisense treatment. FIGS. 6A-D show results for combination therapy using a bispecific antisense targeting both IGFBP-2 and IGFBP-5 and anti-clusterin antisense.

FIGS. 7A-C shows results for treatment of PC-3 cells with combination therapy using a bispecific antisense targeting both IGFBP-2 and IGFBP-5 and anti-clusterin antisense.

FIGS. 8A-E shows results for treatment of PC-3 cells with combination therapy using a bispecific antisense targeting both IGFBP-2 and IGFBP-5 and anti-clusterin antisense.

DETAILED DESCRIPTION OF THE INVENTION Definitions

Definition and Sequences for IGFBP 2/5

As used in the specification and claims of this application, the terms “insulin-dependent growth factor-2” and “IGFBP-2” are used interchangeably. The nucleotide sequence of human IGFBP-2 is known from NCBI sequence accession no. NM_(—)000597 and is set forth in Seq. ID No. 52.

As used in the specification and claims of this application, the terms “insulin-dependent growth factor-5” and “IGFBP-5” are used interchangeably. The nucleotide sequence of human IGFBP-2 is known from NCBI sequence accession no. NM_(—)000599 and is set forth in Seq. ID No. 53.

As used in the specification and claims of this application, the term “clusterin” refers to the glycoprotein originally derived from ram rete testes, and to homologous proteins derived from other mammalian species, including humans, whether denominated as clusterin or an alternative name. The sequences of numerous clusterin species are known. For example, the sequence of human clusterin is reported by Wong et al., (1994) [2], and in NCBI sequence accession number NM_(—)001831 and is set forth in Seq. ID No.: 1. In this sequence, the coding sequence spans bases 48 to 1397.

As used in this application, the term “amount of clusterin” refers to the amount of clusterin which is present in a form which is functional to provide anti-apoptotic protection. The effective amount of clusterin may be reduced through restricting production of clusterin (at the transcription or translation level) or by degrading clusterin at a rate faster than it is being produced. Further, it will be appreciated that inhibition occurs when the clusterin would otherwise be present if the antisense oligonucleotide had not been administered.

As used in this application, the term “amount of IGFBP-2 and/or IGFBP-5” refers to the amount of the binding protein which is present.

As used in the specification, “antisense oligonucleotide” refers to stretches of single-stranded DNA, usually chemically modified, whose sequence (3′→5′) is complementary to the sense sequence of a molecule of mRNA. Antisense molecules thereby effectively inhibit gene expression by forming RNA/DNA duplexes, and offer a more targeted option for cancer therapy than chemotherapy or radiation. Antisense is believed work by a variety of mechanisms, including physically blocking the ability of ribosomes to move along the messenger RNA, and hastening the rate at which the mRNA is degraded within the cytosol. The abbreviation ASO may also be used to refer to an antisense oligonucleotide

As used in the specification and claims of this application, the term “combination” refers to an assemblage of reagents for use in therapy either by simultaneous or contemporaneous administration. Simultaneous administration refers to administration of an admixture (whether a true mixture, a suspension, an emulsion or other physical combination) of the agent that reduces IGFBP-2 and/or IGFBP-5 and the oligonucleotide. In this case, the combination may be the admixture or separate containers of the agent and the oligonucleotide that are combined just prior to administration. Contemporaneous administration refers to the separate administration of the agent and the oligonucleotide at the same time, or at times sufficiently close together that a enhanced or synergistic activity relative to the activity of either the agent or the oligonucleotide alone is observed. In this, the combination comprises separate containers of the agent and the oligonucleotide

Agents that Reduce IGFBP-2 and/or IGFBP-5

The agent used in the combinations and method of the present invention is one that reduced the amount of IGFBP-2 and/or IGFBP-5.

In one embodiment of the invention, this agent is a bispecific agent complementary to portions of the IGFBP-2 and/or IGFBP-5 gene or mRNA, wherein substantially all of the oligodeoxynucleotide consists essentially of a sequence of bases that is complementary to a portion of portions of a gene encoding human IGFBP-2 and substantially all of the oligodeoxynucleotide is also complementary to a gene encoding human IGFBP-5, and wherein the oligodeoxynucleotide which is of sufficient length (in general at least 15 bases) to act as an antisense inhibitor of the effective amount of human IGFBP-2 and human IGFBP-5. Specific bispecific antisense oligonucleotides of this type that can be used as the agent in the invention consist essentially of a series of bases as set forth in Seq. ID. No. 45 through 51 as follows:

Seq ID No.: 45 ggtgtagacgccgcacg Seq ID No.: 46 gcagcgcagcccctgg Seq ID No.: 47 gcagcagccgcagcccggctcc Seq ID No.: 48 agccgcagcccggctcct Seq ID No.: 49 cagcagccgcagcccggctc Seq ID No.: 50 gcagcagccgcagcccggct Seq ID No.: 51 agcagccgcagcccggctcc

These antisense oligonucleotides employed may be modified to increase the stability of the antisense oligonucleotide in vivo. For example, the antisense oligonucleotides may be employed as phosphorothioate derivatives (replacement of a non-bridging phosphoryl oxygen atom with a sulfur atom) which have increased resistance to nuclease digestion. Increased antisense oligonucleotide stability can also be achieved using molecules with 2-methoxyethyl (MOE) substituted backbones as described generally in U.S. Pat. No. 6,451,991 and U.S. patent application Ser. No. 10/080,794 which are incorporated herein by reference. Seq. ID Nos. 4, 5, and 12 herein are shown in U.S. patent application Ser. No. 10/080,794 to be operative for reducing the expression of clusterin, and are identified in U.S. patent application Ser. No. 10/080,794 as See. ID Nos. 45 and 12 respectively.

Reduction in the amount of IGFBP-2 and/or IGFBP-5 can be accomplished using therapeutics, alone or in combination, that target the two binding proteins individually. By way of non-limiting example, antisense species that reduce IGFBP-2 or IGFBP-5 individually are described in International Patent Publication Nos. WO02/22642 and WO01/05435, which are incorporated herein by reference. Seq. ID Nos. 125, 126, and 127 herein are shown in WO02/22642 to be operative for the stated purpose of reducing IGFBP-2, and are identified in that reference as Seq. ID Nos. 1, 2, and 3, respectively. Seq. ID Nos. 128, 129, 130, and 131 herein are shown in WO01/05435 to be operative for the stated purpose of reducing IGFBP-5, and are identified in that reference as Seq. ID Nos. 1, 3, 4, and 10, respectively. Antisense sequences are also disclosed in Huynh, Hung, et al.; “A Role for Insulin-Like Growth Factor Binding Protein 5 in the Antiproliferative Action of the Antiestrogen ICI 182782”; Cell Growth & Differentiation, Vol. 7, No. 11, pages 1501-1506; 1996. Seq. ID No. 132 herein is shown in Huynh et al. to be operative for the stated purpose of reducing IGFBP-5 accumulation.

The amount of antisense oligonucleotide administered is one effective to reduce the effective amount of levels of IGFBP-2 and/or IGFBP-5 in the tumor/cancer cell of concern. As noted above, in the context of the present invention, applicants do not intend to be bound by any specific mechanism by which this reduction may occur, although it is noted that the reduction may occur as a result of reduced expression of IGFBP-2 and -5 if the antisense molecule interferes with translation of the mRNA, or via an RNase mediated mechanism. Furthermore, it will be appreciated that the appropriate therapeutic amount will vary both with the effectiveness of the specific antisense oligonucleotide employed, and with the nature of any carrier used. The determination of appropriate amounts for any given composition is within the skill in the art, through standard series of tests designed to assess appropriate therapeutic levels

The combination and method of the invention can also be practiced using siRNA molecules to reduce IGFBP-2 and/or IGFBP-5. By way of non-limiting example, antisense species that reduce IGFBP-2 or IGFBP-5 individually are described in International Patent Publication No. WO2004/018676, which is incorporated herein by reference. Seq. ID Nos. 133-138 herein are shown in WO2004/018676 to be operative for the stated purpose of reducing IGFBP-2 and/or IGFBP-5, and are identified in WO2004/018676 as Seq. ID Nos. 39-44, respectively

Reduction in the amount of IGFBP-2 and/or 5 may also be obtained using a fusion protein that contains distinct regions that target the two proteins. By way of non-limiting example, such a fusion protein is disclosed in U.S. Pat. No. 5,929,040, which is incorporated herein by reference.

Other molecules that can be used to reduce the amount of IGFBP-2 and/or IGFBP-5 include therapeutic antibodies such as those described in International Patent Publication No. WO00/69454. Seq. ID No. 139 herein is shown in WO00/69454 to be operative for the purpose of generating antibodies, and is identified in WO00/69454 as Seq. ID No. 3.

Oligonucleotides

Antisense Oligonucleotides (ASO) Antisense oligonucleotides are synthetic polymers made up of monomers of deoxynucleotides like those in DNA. In the present application, the term antisense oligonucleotides includes antisense oligodeoxynucleotides.

The antisense oligonucleotides for use in the combination and method of the invention for treatment of cancer in humans may be complementary to the nucleotide sequence of human clusterin as set forth in Seq. ID No. 1. Exemplary sequences which can be employed as antisense oligonucleotides in the combination and method of the invention are disclosed in PCT Patent Publication WO 00/49937, US Patent Publication US-2002-0128220-A1, and U.S. Pat. No. 6,383,808, all of which are incorporated herein by reference in those jurisdictions where such incorporation is permitted. Seq. ID Nos. 4, 5, and 12 herein are shown in PCT Patent Publication WO 00/49937 to be operative for the purpose of reducing clusterin, and are identified in PCT Patent Publication WO 00/49937 as Seq. ID Nos. 4, 5, and 12. Seq. ID Nos. 4, 5, and 12 herein are shown in US Patent Publication US-2002-0128220-A1 to be operative for the purpose of reducing clusterin, and are identified in PCT Patent Publication US Patent Publication US-2002-0128220-A1 as Seq. ID Nos. 4, 5, and 12. Seq. ID Nos. 54-123 herein are shown in U.S. Pat. No. 6,383,808 to be operative for the purpose of inhibiting the expression of clusterin, and are identified in United States published patent application U.S. Pat. No. 6,383,808 as Sec. ID Nos. 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 69, 70, 71, 72, 73, 74, 76, 78, 79, 80, 82, 83, 84, 85, 86, 87, 88 and 89, respectively. In specific embodiments, the antisense oligonucleotide may span either the translation initiation site or the termination site of clusterin. The antisense oligonucleotide comprises and may consist essentially of an oligonucleotide selected from the group consisting of Seq. ID. Nos.: 2 to 19 as shown in Table 1, or more specifically Seq. ID. No. 4, Seq. ID. No. 5 and Seq. ID. No. 12.

TABLE 1 Seq ID No. Description SEQUENCE (5′ to 3′) 2 Antisense TRPM-2 GCACAGCAGGAGAATCTTCAT oligonucleotide 3 Antisense TRPM-2 TGGAGTCTTTGCACGCCTCGG oligonucleotide 4 Antisense oligo- CAGCAGCAGAGTCTTCATCAT nucleotide  corresponding to  the human TRPM-2  translation initiation site 5 Antisense TRPM-2 ATTGTCTGAGACCGTCTGGTC oligonucleotide 6 Antisense TRPM-2 CCTTCAGCTTTGTCTCTGATT oligonucleotide 7 Antisense TRPM-2 AGCAGGGAGTCGATGCGGTCA oligonucleotide 8 Antisense TRPM-2 ATCAAGCTGCGGACGATGCGG oligonucleotide 9 Antisense TRPM-2 GCAGGCAGCCCGTGGAGTTGT oligonucleotide 10 Antisense TRPM-2 TTCAGCTGCTCCAGCAAGGAG oligonucleotide 11 Antisense TRPM-2 AATTTAGGGTTCTTCCTGGAG oligonucleotide 12 Antisense TRPM-2 GCTGGGCGGAGTTGGGGGCCT oligonucleotide 13 Antisense TRPM-2 GGTGTAGACG CCGCACG oligonucleotide 14 Antisense TRPM-2 GCAGCGCAGC CCCTGG oligonucleotide 15 Antisense TRPM-2 GCAGCAGCCG CAGCCCGGCT CC oligonucleotide 16 Antisense TRPM-2 AGCCGCAGCC CGGCTCCT oligonucleotide 17 Antisense TRPM-2 CAGCAGCCGC AGCCCGGCTC oligonucleotide 18 Antisense TRPM-2 GCAGCAGCCG CAGCCCGGCT oligonucleotide 19 Antisense TRPM-2 AGCAGCCGCAGCCCGGCTCC oligonucleotide 20 2 base TRPM-2 CAGCAGCAGAGTATTTATCAT mismatch oligo- nucleotide used as a control

As used in the specification and claims of this application, the phrase “consist essentially of” means that the oligonucleotide contains just the based of the identified sequence or such bases and a small number of additional bases that do not materially alter the antisense function of the oligonucleotide.

In order avoid digestion by DNAse, antisense oligonucleotides and ODNs are often chemically modified. For example, phosphorothioate oligodeoxynucleotides are stabilized to resist nuclease digestion by substituting one of the non-bridging phosphoryl oxygen of DNA with a sulfur. Increased antisense oligonucleotide stability can also be achieved using molecules with 2-methoxyethyl (MOE) substituted backbones as described generally in U.S. Pat. No. 6,451,991, incorporated by reference in those jurisdictions allowing such incorporation, and US Published patent application US-2003-0158143-A1. Seq. ID Nos. 45-51 herein are shown in US-2003-0158143-A1 to be operative for the purpose of inhibiting IGFBP-2 and IGFBP-5, and are identified in US-2003-0158143-A1 as Seq. ID Nos. 1-7, respectively. Thus, in the combination and method of the invention, the antisense oligonucleotide be modified to enhance in vivo stability relative to an unmodified oligonucleotide of the same sequence. The modification may be a (2′-O-(2-methoxyethyl) modification. The oligonucleotide may have a phosphorothioate backbone throughout, the sugar moieties of nucleotides 1-4 and 18-21 may bear 2′-O-methoxyethyl modifications and the remaining nucleotides may be 2′-deoxynucleotides.

The antisense oligonucleotide may be a 5-10-5 gap-mer methoxyl ethyl modified (MOE) oligonucleotide corresponding to SEQ ID NO.: 5 below. The antisense oligonucleotide may be from 10-25 bases in length, or from 15-23 bases in length, or from 18-22 bases in length, or 21 bases in length. A particularly preferred antisense oligonucleotide is a 21 mer oligonucleotide (CAGCAGCAGAGTCTTCATCAT; SEQ ID NO.: 4) targeted to the translation initiation codon and next 6 codons of the human clusterin sequence with a 2′-MOE modification. In one embodiment, this oligonucleotide has a phosphorothioate backbone throughout. The sugar moieties of nucleotides 1-4 and 18-21 (the “wings”) bear 2′-O-methoxyethyl modifications and the remaining nucleotides (nucleotides 5-17; the “deoxy gap”) are 2′-deoxynucleotides. Cytosines in the wings (i.e., nucleotides 1, 4 and 19) are 5-methylcytosines.

RNAi Oligonucleotides

Reduction in the amount of clusterin may also be achieved using RNA interference or “RNAi”. RNAi is a term initially coined by Fire and co-workers to describe the observation that double-stranded RNA (dsRNA) can block gene expression[3]. Double stranded RNA, or dsRNA directs gene-specific, post-transcriptional silencing in many organisms, including vertebrates. RNAi involves mRNA degradation, but many of the biochemical mechanisms underlying this interference are unknown. The use of RNAi has been further described[3,4].

The initial agent for RNAi is a double stranded RNA molecule corresponding to a target nucleic acid. The dsRNA is then thought to be cleaved in vivo into short interfering RNAs (siRNAs) which are 21-23 nucleotides in length (19-21 bp duplexes, each with 2 nucleotide 3′ overhangs). Alternatively, RNAi may be effected via directly introducing into the cell, or generating within the cell by introducing into the cell a suitable precursor (e.g. vector, etc.) of such an siRNA or siRNA-like molecule. An siRNA may then associate with other intracellular components to form an RNA-induced silencing complex (RISC).

RNA molecules used in embodiments of the present invention generally comprise an RNA portion and some additional portion, for example a deoxyribonucleotide portion. The total number of nucleotides in the RNA molecule is suitably less than 49 in order to be effective mediators of RNAi. In preferred RNA molecules, the number of nucleotides is 16 to 29, more preferably 18 to 23, and most preferably 21-23.

In certain embodiments of the invention, the siRNA or siRNA-like molecule is less than about 30 nucleotides in length. In a further embodiment, the siRNA or siRNA-like molecules are about 21-23 nucleotides in length. In an embodiment, siRNA or siRNA-like molecules comprise and 19-21 bp duplex portion, each strand having a 2 nucleotide 3′ overhang.

In certain embodiments of the invention, the siRNA or siRNA-like molecule is substantially identical to a clusterin-encoding nucleic acid or a fragment or variant (or a fragment of a variant) thereof. Such a variant is capable of encoding a protein having clusterin-like activity. In some embodiments, the sense strand of the siRNA or siRNA-like molecule is targeted to the same portion of the DNA as antisense SEQ ID NO: 4 or a fragment thereof (RNA having U in place of T residues of the DNA sequence). In other embodiments, the RNAi sequence consists of Seq. Id. No. 41 or 43. For example, United States published patent application 2004096882 discloses RNAi therapeutic probes targeting clusterin. In addition, reagents and kits for performing RNAi are available commercially from for example Ambion Inc. (Austin, Tex., USA) and New England Biolabs Inc. (Beverly, Mass., USA). Suitable sequences for use as RNAi in the present invention are set forth in the present application as Seq. ID Nos. 21 to 44 as shown in Table 2.

TABLE 2 SEQ ID No. Description SEQUENCE 21 RNAi for human GUAGAAGGGC GAGCUCUGGTT clusterin 22 RNAi for human GAUGCUCAACACCUCCUCCT T clusterin 23 RNAi for human GGAGGAGGUG UUGAGCAUCT T clusterin 24 RNAi for human CUAAUUCAAU AAAACUGUCT T clusterin 25 RNAi for human GACAGUUUUA UUGAAUUAGT T clusterin 26 RNAi for human UAAUUCAACA AAACUGUTT clusterin 27 RNAi for human ACAGUUUUGU UGAAUUATT clusterin 28 RNAi for human AUGAUGAAGA CUCUGCUGCT T clusterin 29 RNAi for human GCAGCAGAGU CUUCAUCAUT T clusterin 30 RNAi for human UGAAUGAAGG GACUAACCUG TT clusterin 31 RNAi for human CAGGUUAGUC CCUUCAUUCA TT clusterin 32 RNAi for human CAGAAAUAGA CAAAGUGGGG TT clusterin 33 RNAi for human CCCCACUUUG UCUAUUUCUG TT clusterin 34 RNAi for human ACAGAGACUA AGGGACCAGA TT clusterin 35 RNAi for human ACAGAGACUA AGGGACCAGA TT clusterin 36 RNAi for human CCAGAGCUCG CCCUUCUACT T clusterin 37 RNAi for human GUAGAAGGGC GAGCUCUGGT T clusterin 38 RNAi for human GUCCCGCAUC GUCCGCAGCT T clusterin 39 RNAi for human GCUGCGGACG AUGCGGGACT T clusterin 40 RNAi for human CUAAUUCAAU AAAACUGUCT T clusterin 41 RNAi for human GACAGUUUUA UUGAAUUAGT T clusterin 42 RNAi for human AUGAUGAAGA CUCUGCUGC clusterin 43 RNAi for human GCAGCAGAGU CUUCAUCAU clusterin 44 RNAi for human CCAGAGCUCG CCCUUCUACT T clusterin Cancers that can be Treated

The combination of the present application is useful in the treatment of a variety of cancers for which IGFBP-2 and/or IGFBP-5 is considered relevant. Such cancers include without limitation endocrine-regulated tumors, for example, breast, prostate, ovarian and colon cancers. Determination of whether a given agent used in the treatment of cancer by reduction of IGFBP-2 and/or IGFBP-5 results in enhancement of clusterin expression can be readily determined using Northern blot or other techniques to detect clusterin mRNA or protein in the presence and absence of the agent. Those agents that result in enhanced clusterin expression may be made more effective through use in combination with an oligonucleotide inhibitor of clusterin expression

Methods

Administration of antisense ODNs can be carried out using the various mechanisms known in the art, including naked administration and administration in pharmaceutically acceptable lipid carriers. For example, lipid carriers for antisense delivery are disclosed in U.S. Pat. Nos. 5,855,911 and 5,417,978. In general, the antisense is administered by intravenous, intraperitoneal, subcutaneous or oral routes, or direct local tumor injection.

The amount of antisense ODN administered is one effective to reduce the expression of clusterin in cancer cells. It will be appreciated that this amount will vary both with the effectiveness of the antisense ODN employed, and with the nature of any carrier used. The determination of appropriate amounts for any given composition is within the skill in the art, through standard series of tests designed to assess appropriate therapeutic levels. In one embodiment, the antisense ODN is administered to a human patient in an amount of between 40-640 mg, or more particularly, from 300-640 mg. In another embodiment, the antisense ODN is administered according to the weight of the subject in need of the treatment. For example, the antisense ODN may be provided at a dosage of from 1 to 20 mg/kg of body weight.

The amount of and route of administration for the agent targeted to IGFBP-2 and/or IGFBP-5 will of course depend on the agent employed. In the case of antisense the amount administered is one effective to reduce the effective amount of levels of IGFBP-2 and/or IGFBP-5 in the endocrine-regulated tumor cell of concern. As noted above, in the context of the present invention, applicants do not intend to be bound by any specific mechanism by which this reduction may occur, although it is noted that the reduction may occur as a result of reduced expression of IGFBP-2 and -5 if the antisense molecule interferes with translation of the mRNA, or via an RNase mediated mechanism. Furthermore, it will be appreciated that the appropriate therapeutic amount will vary both with the effectiveness of the specific antisense oligonucleotide employed, and with the nature of any carrier used. The determination of appropriate amounts for any given composition is within the skill in the art, through standard series of tests designed to assess appropriate therapeutic levels.

Additional Therapeutic Agents

The method for treating cancer in accordance with one embodiment of the invention may further include administration of chemotherapy agents or other agents useful in breast cancer therapy and/or additional antisense ODNs directed at different targets in combination with the therapeutic effective to reduce the amount of active clusterin. For example, antisense clusterin ODN may be used in combination with more conventional chemotherapy agents such as taxanes (paclitaxel or docetaxel), mitoxanthrone, doxorubicin, gemcitabine, cyclophosphamide, decarbazine, topoisomerase inhibitors), angiogenesis inhibitors, differentiation agents and signal transduction inhibitors.

The application is further described in the following non-limiting examples.

EXAMPLES

Materials and Methods

Phosphorothioate oligonucleotides used in this study to target clusterin were purchased from La Jolla Pharmaceuticals Co. (La Jolla, Calif., USA) or provided by OncoGenex Technologies Inc., Vancouver, Canada. The sequence of the clusterin ASO used corresponded to the human clusterin translation initiation site (5′-CAGCAGCAGAGTCTTCATCAT-3′) (SEQ ID NO.: 4). A 2-base clusterin mismatch oligonucleotide (5′-CAGCAGCAGAGTATTTATCAT-3′) (SEQ ID NO.: 20) was used as control. Oligonucleotides were delivered into cells in form of complexes with the Lipofectin™ transfection reagent (Invitrogen). Cells were incubated with different concentrations of oligonucleotides and Lipofectin™ for 6 hours in OPTIMEM™ medium (Gibco). At the end of oligonucleotide treatment, the medium was replaced with fresh growth medium containing 2% of fetal calf serum and at different time points, cells were processed according to the various analyses to be performed.

Example 1

LNCaP cells were treated with treated with 500 nM concentrations of antisense oligonucleotides of Seq. ID Nos. 45, 46 or 47 or a mismatch control. Levels of IGFBP-2 were measured. The results are summarized in FIG. 1A.

PC3 cells were treated with treated with 500 nM concentrations of antisense oligonucleotides of Seq. ID Nos. 45, 46 or 47 or a mismatch control. Levels of IGFBP-5 were measured. The results are summarized in FIG. 1B

Example 2

Bispecific antisense oligonucleotides were used to treat PC3, LNCaP and bone cells at concentration of 500 nm, and the amount of inhibition of IGFBP-2 or IGFBP-5 was measured using real time PCR. Oligonucleotides of Seq. ID Nos. 46, 48, 49 and 51 were tested, and all were effective to reduce the detected amount of the IGFBP measured. (FIG. 2A) Reductions of up to 70% in IGFBP-2 levels were also observed in A549 lung cells using 500 nM of Seq. ID Nos. 48 and 49. (FIG. 2B) Seq. ID No. 48 (500 nM) was also shown to be effective to inhibit cell growth of LNCaP cells and reduce the cell number by more than 90%. (FIG. 2C) FIGS. 2D and E respectively show results for inhibition of IGFBP-5 levels in PC3 cells with 500 nM of Seq ID Nos. 45, 46, 48, 49, 50 and 51; and inhibition of IGBFP-5 levels in human fetal bone fobroblast cells with 500 nM of Seq. ID Nos. 45, 46, 48, 49, 50 and 51.

Example 3

Real time PCR was used to measure the amount IGFBP-5 in MSF human fetal fibroblast cells after treatment with antisense oligonucleotide and LIPOFECTIN (4 μg/ml). Cells were plated in vitro and treated with a four-hour pulse of 500 nM oligonucleotide followed by a 20 hour period in normal medium plus 5% serum. A second four-hour pulse was repeated on day 2 and the cells were counted on day 3. The most active antisense oligonucleotides were Seq. ID Nos. 48 and 49. (FIG. 5)

Example 4

Real time PCR was used to evaluate the amounts of IGFBP-2 and IGFBP-5 in human bladder cancer (RT4) following treatment with varying amounts of antisense oligonucleotides (Seq. ID Nos. 48 and 49) and 4 μg/ml LIPOFECTIN. As shown in FIGS. 3 and 4, a dose dependent response was observed to both antisense oligonucleotides at concentrations ranging from 50 to 500 nM.

Example 5

Bispecific antisense (cagcagccgcagcccggctc, Seq. ID No. 49) targeted to IGFBP-2 and IGFBP-5 was found to induce apoptosis triggered expression of the stress-associated cytoprotective chaperone, clusterin in two prostate cancer cell lines. LNCaP and PC-3 cells were treated with the antisense and clusterin levels assessed by Western blotting. Full length clusterin was up-regulated by treatment with the bispecific antisense in PC-3 and LNCaP cells, while no significant changes were observed with control ODN. Endogenous clusterin expression in PC-3 cells increased by about 75%. Clusterin expression in LNCaP cells was almost undetectable under basal conditions, but increase >20 fold after treatment with the bispecific antisense.

Example 6

We next tested whether the bispecific antisense-induced up-regulation of clusterin could be inhibited using anti-clusterin antisense using a second generation MOE-gapmer ASO targeting the translation initiation site of clusterin (Seq. ID No. 4). PC-3 and LNCaP cells were treated with 100 nM of the bispecific antisense (its approximate IC50 in PC-3 and LNCaP cells), plus various concentrations of anti-clusterin antisense or control ODN, and clusterin levels were analyzed by Western blotting. In both cell lines, bispecific-antisense-induced up-regulation of clusterin was significantly inhibited by the anti-clusterin antisense.

Example 7

We next tested whether anti-clusterin antisense knockdown of bispecific antisense-induced increases in clusterin enhanced apoptotic rates. PC-3 and LNCaP cells were treated daily with 100 nM of the bispecific antisense and various concentrations of anti-clusterin antisense or control ODN for 2 days. After 72 hours incubation, cell viability was determined by the MTT or crystal violet assay, respectively. As shown in FIGS. 6, A and B, the combination with the anti-clusterin antisense significantly enhanced the cytotoxicity of the bispecific antisense in a dose-dependent manner in both PC-3 and LNCaP cells. In contrast, the anti-clusterin antisense had no effects on apoptotic rates when used alone. Combined treatment of bispecific antisense plus anti-clusterin antisense significantly increased the sub G0/G1 fraction compared to controls in both PC-3 and LNCaP cells (FIGS. 6C and D). We further evaluated the effects of combined treatment on apoptosis using Western blot analysis to identify PARP cleavage, a substrate for caspases activated during apoptotic execution (Labnik et al. Nature 371: 346-347 (1994). In PC-3 cells the 85 kD PARP cleaved fragment was detected only after combined treatment with >100 nM of anti-clusterin antisense treatment. Similarly, increased levels of cleaved PARP was detected in LNCaP cells after treatment with bispecific antisense plus >100 nM anti-clusterin antisense.

Example 8

We next tested whether the in vitro observations above could be recapitulated in vivo. Male mice bearing PC-3 tumors (100 mm³) were randomly selected for treatment with bispecific antisense plus anti-clusterin antisense, anti-clusterin antisense plus control ODN, bispecific antisense plus control ODN or control ODN alone. Each treatment group consisted of 10 mice and each mouse received 12.5 mg/kg of bispecific antisense, anti-clusterin antisense and/or control ODN administrated once daily by i.p. during the first week and 3 times per week thereafter. Treatments were continued for 5 weeks after starting ASO injection. Under this experimental condition, no adverse effects were observed. As shown in FIG. 7A, bispecific antisense plus control ODN treatment reduced PC-3 tumor volume by 41% compared to control ODN alone (p<0.05), whereas no significant difference was observed between anti-clusterin antisense plus control ODN or control ODN alone treatment groups. Combined treatment of bispecific antisense plus anti-clusterin antisense significantly inhibited PC-3 tumor growth by 52, 64 and 71% compared to bispecific antisense, anti-clusterin antisense and control ODN treatment groups, respectively. Total RNA was extracted from each tumor after sacrifice and assessed for changes in mRNA levels of IGFBP-5 and clusterin using Northern blot analysis. As shown in FIGS. 7B and C, mRNA levels of IGFBP-5 in PC-3 tumors were significantly reduced by bispecific antisense containing treatment regimen when compared to other treatment regimens. Similarly, mRNA levels of clusterin in PC-3 tumors were significantly reduced by anti-clusterin antisense containing regimen compared to other treatment regimens. Clusterin mRNA level was increased after treatment with bispecific antisense plus control ODN by 15% compared to control ODN alone. Mice bearing subcutaneous LNCaP tumors were castrated and treated with the same schedule described above for PC-3 tumors. Each treatment group consisted of 10 mice. As shown in FIG. 8A, anti-clusterin antisense plus control ODN treatment significantly reduced LNCaP tumor volume by 47% compared to control ODN alone (p<0.01). Although bispecific antisense plus control ODN treatments reduced LNCaP tumor volume by 22% compared to control ODN alone, the difference did not reached statistical significance. Combined treatment with bispecific antisense and anti-clusterin antisense significantly inhibited LNCaP tumor growth by 61, 57 and 77% compared to bispecific antisense, anti-clusterin antisense and control ODN treatment groups, respectively. Serum PSA decreased by approximately 80% by 2 weeks in all treatment groups after castration, and then increased in the control ODN and bispecific antisense plus control ODN groups by 2.5- and 1.5-fold, respectively by 8 weeks post castration. Serum PSA in anti-clusterin antisense plus control ODN and anti-clusterin antisense plus bispecific antisense treatment group remained below baseline levels for longer than 8 weeks post treatment (FIG. 8B). Total RNA was extracted from each tumor after sacrifice and assessed for changes in mRNA levels of clusterin, IGFBP-2 and IGFBP-5 using Northern blot analysis. As shown in FIGS. 8, C, D, and E, mRNA levels of clusterin in LNCaP tumors were significantly reduced by anti-clusterin antisense containing regimen compared to other treatment regimens. Similarly, mRNA levels of IGFBP-2 and IGFBP-5 in LNCaP tumors were significantly decreased by bispecific antisense containing treatment regimen when compared to other treatment regimens. Clusterin mRNA level was significantly increased after treatment with bispecific antisense plus control ODN by 2-fold compared to control ODN alone. These data, observed both in PC-3 and LNCaP tumor model, mirror the in vitro observations above, with bispecific antisense-induced up-regulation of clusterin and anti-clusterin antisense mediated suppression of bispecific antisense-induced clusterin up-regulation.

All of the cited documents are incorporated herein by reference in those jurisdictions allowing such incorporation.

While specific embodiments of the invention have been described and illustrated, such embodiments should be considered illustrative of the invention only and not as limiting the invention.

REFERENCES

-   1. Wong et al., Eur. J. Biochem. 221 (3), 917-925 (1994) -   2. Sensibar et al., Cancer Research 55: 2431-2437 (1995) -   3. Fire et al. (1998) Nature 391, 806-811 -   4. Carthew et al. (2001) Current Opinions in Cell Biology 13,     244-248. 

The invention claimed is:
 1. A therapeutic combination for treatment of cancer comprising (a) means for reducing IGFBP-2 and/or IGFBP-5 in cancer cells; and (b) means for reducing the effective amount of clusterin in cancer cells. 